Variable-rate pump



P 1966 H. D. BRAILSFORD VARIABLE-RATE PUMP Filed Nov. 20, 1963 a .g F

2 INVENTOR Harrigon 1). Brailsford BY I HIS ATTORNEY United StatesPatent 3,246,604 VARIABLE-RATE PUMP Harrison D. Brailsford, 670 MiltonRoad, Rye, N.Y. Filed Nov. 20, 1963, Ser. No. 325,045 4 Claims. (Cl.103-38) This invention relates to pumps of the type described in myUnited States Patent 3,059,586 and particularly to means for varying thestroke, and hence the pumping rate, thereof.

My previous pumps operated with a fixed stroke, which meant that theonly way that the amount of fluid that they pumped in a given length oftime could be varied was by controlling the number of revolutions turnedby the crankshaft of the pump in that length of time. This, in turn,required either a variable-speed transmission between the driving motorand the pump, or a motor having controllable speed, or means forrendering the motor inoperative during part of the time. Each of theseexpedients has its own drawbacks: a variable-speed transmission iscomplicated, space-consuming, and expensive; at speed control,particularly in the unattended operation to which these pumps aresubjected, tends to be inaccurate and ineflicient; and in order to turnoff the motor for predetermined intervals, a relatively expensive andcomplicated timer is required.

It is one of the principal objects of this invention to provide simple,inexpensive, and relatively accurate and constant means for controllingthe stroke, and hence, pumping speed, of a pump of the type described inthe aforesaid Patent 3,059,586.

Other objects are to provide means for varying the stroke withoutlimiting the extent of angular excursions of the pump and to control thestroke by limiting the distance to which the piston is moved away fromthe inlet-outlet channel of the pump.

In accordance with the invention, I have provided a slotted yokeattached to the piston rod of the pump with the slot extending in thesame direction as the piston rod. The crankpin of an eccentric fits intothe slot to move therein to tilt the pump cylinder between its fixed,angular limits and to draw the piston back and forth in the cylinder.Means are also provided to change the length of that portion of the slotin which the crankpin is free to move. Further in accordance with theinvention, the crankpin is restricted to that portion of the slotstarting with, and always including, that point in the slot nearest thepiston rod.

The invention will be further described in connection with the drawingsin which:

FIG. 1 is a front view of a pump constructed according to the invention;

FIG. 2 is a cross-sectional view of the pump in FIG. 1 taken along theline 22;

FIG. 3 shows a front view of the pump of FIG. 1 in a different part ofits operating cycle and with a modified stroke control; and

FIG. 4 is a cross-sectional view along the line 44 in FIG. 2 and showsthe relative positions of the inlet and outlet channels of the pump ofFIGS. 1-3.

The pump in FIG. 1 comprises a base plate 11 on which is mounted anelectric motor 12 driving, by means of a pinion (not shown), a gear 13.The latter is afiixed to a shaft 14 which constitutes the crankshaft ofthe pump and has an eccentric 16 with a crankpin 17. The latter fitsrelatively snugly with a slot 18 in a yoke 19 attached to one end of apiston rod 21, the other end of which is affixed to a piston 22 with acylinder 23. The piston has a gasket, or piston ring, in the form of anO-ring 24 to prevent leakage of the pumped fluid past the piston.Preferably both the piston 22 and the cylinder 23 are made of plastic,although the cylinder has one end closed 3,246,604 Patented Apr. '19,1966 by a cylinder head which may be held fast Within a metal ring 26attached to the end of the cylinder by bayonet pin means including a pin27 and a slot 28.

The other end of the cylinder is also closed, at least sufliciently tojournal the piston rod 21 so that the cylinder will tilt substantiallyexactly in step with tilting of the rod as the eccentric 16 is rotated.To permit tilting of the cylinder, the latter is mounted on a pivotallymounted plate 29 which is free to pivot at least to an extent determinedby operating principles to be described hereinafter. The pivot axis ofthe plate 29 is parallel to the axis of the crankshaft 14 and passesthrough the axis of the cylinder 23 in a perpendicular direction.

A channel 31 in the back wall of the cylinder facing the plate 29 andclose to the closed end of the cylinder forms both the inlet and theoutlet channel for fluid being pumped by the pump. In the view shown inFIG. 1, the cylinder 23 is pivoted counterclockwise to an extent which,while less than the maximum, is enough to permit the channel 31 tocommunicate with an inlet pipe 32 in the plate 11. An outlet pipe 33 isspaced a shorter angular distance away from the inlet pipe, and, likethe latter, the outlet pipe extends through the base plate 11.

At the upper end of the yoke 19 is a control means in the form of ascrew 34 which may be screwed in or out to change the lost motion, ordistance through which the crankpin 17 may move lengthwise along theslot 18. It should be noted that, no matter how the screw 34 ispositioned, the crankpin 17 always goes to the bottom end of the slot 18during one point of each rotation of the eccentric 16. This assures goodvolumetric efficiency and that the fluid will be substantially entirelypushed out of the closed end of the cylinder 23 at one point in eachcycle of operation.

The effect of unscrewing the screw 34 will be to provide more lostmotion and thus to limit the length of stroke of the piston 22. At thesame time, the fact that the crankpin 17 substantially fills the widthof the slot 18 assures that the cylinder 23 will be tilted back andforth between exactly the same limits, as required to permit theinlet-outlet channel 31 to communicate with both the inlet pipe 32 andthe outlet pipe 33.

FIG. 2 shows a cross-section of the pump in FIG. 1 and makes more clearthe arrangement of the channel 31 through the plate 29. As may be seen,there is a gasket 34 between the base plate 11 and the pivot plate 29 toprevent leakage of fluid passing through the channel 31 and, in theposition illustrated, the pipe 32.

The pivot plate 29 is held relatively firmly against the gasket 34 by astud 36 journalled in the base plate 11. Pressure is exerted 'by aspring 37 between a collar 38 and a knob 39 at the end of the stud 36 tohold the pivot plate 29 firmly enough against the gasket. A channel 41may be observed at the end of the cylinder 23 to permit air to reach thespace above the piston 22 and to be driven from such space as the pistonmoves upwardly.

FIG. 3 shows the cylinder 23 tilted over to place the channel 31 inposition to communicate with the outlet pipe 33.

While FIG. 3 shows a pump which is otherwise similar to that in FIG. 1,it does differ in the means for adjusting the stroke. Here, such meansinclude a bridge member 42 fitted across the yoke and pinched into placeby a knurled knob 43. If desired, the yoke may be calibrated as shown toprovide a scale 44 to show how much fluid will be pumped each intervalof time.

FIG. 4 shows a fragment of the plate 29 to illustrate the angularrelationship between the locations of the inlet pipe 32 and the outletpipe 33. Both are reached by holes pierced in the gasket 34, the latterbeing shown in cross-section as out along the partition line 4-4 in FIG.2. The pipes 32 and 33 are spaced apart by an angle A.

J The cylinder 23 must be pivoted through approximately the ,sameanglefor proper operation of the .pump, although the finite width of theinlet-outlet channel 31 and the inlet pipe 32 and the outlet pipe 33makes permissible some departure of the angle of tilt of the cylinderfrom the angle A. p

While this invention has been described in terms of a specificembodiment, it will be understood by those skilled in the art thatmodifications may be made therein within the true scope of the inventionas determined by the following claims.

What is claimed is:

1. A pump comprising: a hollow cylinder closed at one end; a pistonaxially slidable therein; a piston rod having one end rigidly attachedto said piston; a yoke attached to the other end of said piston rodoutside of said cylinder, said yoke having an axially elongated slottherein; a pivotal mounting for said piston to tilt said piston betweentwo limiting positions and about an axis substantially perpendicular tothe axis of said piston; an opening in the Wall of said cylinder nearthe closed end thereof; a pair of of channels, one of said channelscommunicating with said opening when said piston is tilted to one of itslimiting positions and the other of said channels communicating withsaid opening when said piston is tilted to the other of its limitingpositions; an eccentric having a shaft substantially parallel with theaxis of said ,pivotal mounting and an offset pin extending into saidslot of said yoke and substantially filling the Width of said slot topivot said cylinder to both of its limiting positions as said eccentricrotates.

2. A pump comprising: a hollow cylinder closed at .one end; a pistonaxially slidable therein; a piston rod having one end rigidly attachedto said piston; a yoke attached to the other end of said piston rodoutside of said cylinder, said yoke having an axially elongated slot.therein; a pivotaljmounting for said piston to tilt said piston about apivotal axis and between two limiting positions and about an axissubstantially perpendicular to the axis of said piston; an opening inthe wall of said cylinder between said pivotal axis and the closed endthereof; a pair of channels, one of said channels communicating withsaid opening when said piston is tilted to one of its limiting positionsand the other of said channels communicating with said opening when saidpiston is titlted to the other of its limiting positions; an eccentrichaving a shaft substantially parallel with the axis of said pivotalmounting and an offset pin extending into said'slot of said yoke andsubstantially filling the width of said slot to pivot said cylinder toboth of its limiting positions as said eccentric rotates.

3. A pump comprising: a hollow cylinder closed at one end; a pistonaxially slidable therein; a piston rod 4 having-one end rigidly attachedto said piston; a yoke attached to the other end of said piston rodoutside of said cylinder, said yoke having an axially elongated slottherein; a barrier on said yoke to partition off a section of said slot;a pivotal mounting for said piston to tilt said piston between twolimiting positions and about an axis substantially perpendicular to theaxis of said piston; an opening in the wall of said cylinder near theclosed end thereof; a pair of channels, one of said channelscommunicating with said opening when said piston is tilted to one'of itslimiting positions and the other of said channels communicating withsaid opening when said piston is tilted to the other of its limitingpositions; an

eccentric having a shaft substantially parallel with the axis of saidpivotal mounting and an offset pin extending into said slot of said yokebetween said barrier and the end of said slot nearer said piston andsubstantially filling the width of said slot to pivot said cylinder toboth of its limiting positions as said eccentric rotates.

4. A pump-comprisingz a hollow cylinder=closed at one end; a pistonaxially slidable therein; a piston rod having one end rigidly attachedto said piston; a yoke attached to the other end of said piston rodoutside of said cylinder, said yoke having an axially elongated slottherein; a barrier and means to aflix said barrier to selected positionsalong said yoke to partition off a section of said slot; a pivotalmounting for said piston to tilt said piston between two limitingpositions and about an axis substantially perpendicular to the axis ofsaid piston; an opening in the wall of said cylinder near-theclosed endthereof; a pair of channels, one of said channelscommunicating with saidopening when said piston is tilted to one of its limiting positions andthe other of said channels communicating with said opening whensaid'piston is tilted to the other of its limiting positions; aneccentric having a shaft substantially parallel with the axis of saidpivotal mounting and an offset pin extending into said slot of said yokein the section of said slot between said barrier and the end of saidslot nearer said piston and substantially filling the width of said slotto pivot said cylinder to both of its limiting positions as saideccentric rotates. I

References Cited by the Examiner UNITED STATES PATENTS 728,526 5/1903Wantz 23020 891,026 6/1908 Zeitlin 230- 1,648,554 11/1927 Lundin 103-1631,739,252 12/1929 Mojonnier 10338 2,032,163 v, 2/1936 Bagby 10338LAURENCE V. EFNER, Primary Examiner.

1. A PUMP COMPRISING: A HOLLOW CYLINDER CLOSED AT ONE END; A PISTONAXIALLY SLIDABLE THEREIN; A PISTON ROD HAVING ONE END RIGIDLY ATTACHEDTO SAID PISTON; A YOKE ATTACHED TO THE OTHER END OF SAID PISTON RODOUTSIDE OF SAID CYLINDER, SAID YOKE HAVING AN AXIALLY ELONGATED SLOTTHEREIN; A PIVOTAL MOUNTING FOR SAID PISTON TO TILT SAID PISTON BETWEENTWO LIMITING POSITIONS AND ABOUT AN AXIS SUBSTANTIALLY PERPENDICULAR TOTHE AXIS OF SAID PISTON; AN OPENING IN THE WALL OF SAID CYLINDER NEARTHE CLOSED END THEREOF; A PAIR OF OF CHANNELS, ONE OF SAID CHANNELSCOMMUNICATING WITH SAID OPENING WHEN SAID PISTON IS TILTED TO ONE OF ITSLIMITING POSITIONS AND THE OTHER OF SAID CHANNELS COMMUNICATING WITHSAID OPENING WHEN SAID PISTON IS TILTED TO THE OTHER OF ITS LIMITINGPOSITIONS; AN ECCENTRIC HAVING A SHAFT SUBSTANTIALLY PARALLEL WITH THEAXIS OF SAID PIVOTAL MOUNTING AND AN OFFSET PIN EXTENDING INTO SAID SLOTOF SAID YOKE AND SUBSTANTIALLY FILLING THE WIDTH OF SAID SLOT TO PIVOTSAID CYLINDER TO BOTH OF ITS LIMITING POSITIONS AS SAID ECCENTRICROTATES.